Alzheimer's disease (AD) is a progressive neurodegenerative disorder which presents the highest prevalence rate among a number of dementing diseases. The disease may initially affect cognitive abilities such as memory loss and other intellectual abilities, and in the advanced stage, patients may suffer from the loss of motor functions and may require assistance from others in performing basic, daily life activities. Recent studies have revealed that, among the 40 million people worldwide who suffer from dementia, around 60% to 80% of these cases have been classified as Alzheimer's disease. Although the risk factor of Alzheimer's disease is known to increase with age, about 5% of the total AD patients are diagnosed with early onset, i.e. with symptoms first appearing before 65 years of age. As life expectancy continuously rises, it is predicted that the prevalence of AD will drastically increase in the near future.
Despite advancements in medical technology, Alzheimer's disease (AD) is still considered incurable, with the drugs currently available only providing partial relief of the symptoms, but which do not slow down or reverse the degeneration of brain functions caused by the disease. Although the causes of AD have not been clearly identified, one commonly known hypothesis is that the disease may be related to or caused by the abnormal aggregation of beta amyloid (Aβ) proteins in brain tissues of the patient. The ability to identify or detect the presence of these beta amyloid (Aβ) aggregates at an early stage is therefore of significant importance to the diagnosis and treatment of the disease.
Nevertheless, available methods for diagnosing Alzheimer's disease are found to be inadequate and inefficient. For example, a radioactive positron emission tomography (PET) imaging reagent that binds to amyloid plaques was recently approved for clinical use. However, it is known to suffer from the short-comings of high cost, limited availability, toxic radioactivity and particularly, low spatial resolution such that individual plaques are difficult if not impossible to be clearly visualized. Another approach which uses Magnetic Resonance Imaging (MRI) to diagnose Alzheimer's disease involves the use of potentially toxic reagents which limit the maximum safe dosage administrable to a patient and accordingly, limits the sensitivity and accuracy of the method. In this connection, various contrast agents have been developed with an aim to improve or enhance contrast of the detected regions of interest in the MRI images and thus sensitivity of the MRI. For example, chelates of gadolinium have been used as intravenous contrast agents. However, gadolinium is known to exhibit toxicity at high concentration which affects functions of kidney and may even cause renal failure. Recent studies also revealed that, after the use of gadolinium contrast agents during an MRI study, a small amount of at least some forms of gadolinium is found to retain in certain tissues, which may pose a potential risk to the patient.
It is further reported by K K Cheng et al. in Biomaterials 44 (2015) 155-172 published on 12 Jan. 2015 and in US Patent Application Publication No. US 2017/0196998 A1 that iron oxide particles with surfaces coated with curcumin, a naturally occurring compound extracted from turmeric, the root of the Curcuma longa plant, demonstrated ability to bind to beta amyloid (Aβ) plaques in brain tissues of mice and are detectable under MRI. However, the technique still shows insufficiencies in terms of signal sensitivity and spatial resolution in practice for Alzheimer's disease detection, as well as the process in preparing the particles.